In semiconductor components including a drift zone and a drift control zone, when the component is driven in the on state, the drift control zone serves for controlling a conducting channel in the drift zone along a drift control zone dielectric arranged between the drift zone and the drift control zone. The conducting channel brings about a reduction of the on resistance of the component in comparison with such components which do not have a drift control zone.
Such a semiconductor component can be formed as a MOS transistor. In this case the component has, in addition to the drift zone and the drift control zone, a drain zone, a body zone, a source zone and a gate electrode. In this case, the drift zone is arranged between the drain zone and the body zone. The gate electrode serves for controlling a conducting channel in the body zone between the source zone and the drift zone.
The switching behavior of such a MOS transistor is determined by the gate-source capacitance of the transistor and the gate-drain capacitance of the transistor. This denotes parasitic capacitances between the gate electrode and the source zone, and between the gate electrode and the drain zone. A MOS transistor having a drift control zone has in the on state a significantly lower on resistivity (product of on resistance Ron and required chip area A) than a conventional MOS transistor. For the same on resistance as a conventional MOS transistor, such a MOS transistor having a drift control zone can thus be realized with a smaller space outlay, that is to say chip area requirement. When the chip area is reduced, the abovementioned capacitances that influence the switching behavior are also reduced in a corresponding manner. A reduction of the capacitances leads to a steepening of switching edges when the MOS transistor is switched on and off, that is to say to particularly steep edges of a current flowing through the transistor or of a voltage present across the transistor. This can lead to problems particularly when the MOS transistor is used for switching inductive loads without a freewheeling element or a freewheeling current branch being present, or when a load driven by the MOS transistor has large parasitic inductances. Rapid changes in a current flowing through the MOS transistor can lead to undesirable voltage spikes in the circuit overall and especially at the MOS transistor, the voltage spikes being brought about by the inductances.